#  A contract code about NFT

**Published by:** [521918.eth](https://paragraph.com/@521918-eth/)
**Published on:** 2023-01-20
**URL:** https://paragraph.com/@521918-eth/a-contract-code-about-nft

## Content

here is an example contract code for an NFT (non-fungible token) using the Solidity programming language for the Ethereum blockchain: pragma solidity ^0.8.0; contract NFT { // Events event Transfer(address indexed from, address indexed to, uint256 tokenId); event Approval(address indexed owner, address indexed approved, uint256 tokenId);// Variables mapping(uint256 => address) public tokenOwner; mapping(uint256 => address) public tokenApproval; mapping(address => mapping(uint256 => bool)) public ownedTokens; mapping(address => mapping(uint256 => bool)) public approvedTokens; address public owner; // Functions constructor() public { owner = msg.sender; } function mint(address to, uint256 tokenId) public { require(msg.sender == owner, "Only owner can mint new tokens."); require(!tokenOwner[tokenId], "Token with this ID already exists."); tokenOwner[tokenId] = to; ownedTokens[to][tokenId] = true; emit Transfer(address(0), to, tokenId); } function transfer(address to, uint256 tokenId) public { require(tokenOwner[tokenId] == msg.sender, "You do not own this token."); require(to != address(0), "Cannot transfer to address 0x0."); clearApproval(tokenId); tokenOwner[tokenId] = to; ownedTokens[msg.sender][tokenId] = false; ownedTokens[to][tokenId] = true; emit Transfer(msg.sender, to, tokenId); } function approve(address approved, uint256 tokenId) public { require(tokenOwner[tokenId] == msg.sender, "You do not own this token."); tokenApproval[tokenId] = approved; approvedTokens[msg.sender][tokenId] = true; emit Approval(msg.sender, approved, tokenId); } function clearApproval(uint256 tokenId) public { require(tokenOwner[tokenId] == msg.sender, "You do not own this token."); tokenApproval[tokenId] = address(0); approvedTokens[msg.sender][tokenId] = false; } function takeOwnership(uint256 tokenId) public { require(tokenApproval[tokenId] == msg.sender, "You are not approved to take this token."); clearApproval(tokenId); tokenOwner[tokenId] = msg.sender; ownedTokens[tokenApproval[tokenId]][tokenId] = false; ownedTokens[msg.sender][tokenId] = true; emit Transfer(tokenApproval[tokenId], msg.sender, tokenId); } } This code creates a smart contract for an NFT that allows for minting new tokens, transferring ownership of tokens, approving other addresses to take ownership, and taking

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